Download the accompanying student worksheet under "Downloads."
What did Earth look like 250 million years ago? Or 1 billion years ago? Or 4.5 billion years ago? EarthViewer is an interactive tool that allows you to explore the science of Earth's deep history.

(8 min 3 sec) Watch researchers follow brown spider monkeys in a tropical forest of Colombia to determine which plant seeds they are dispersing. Seed dispersers are critical to the forest’s ability to grow and regenerate.

Two species of lionfish, the red lionfish (Pterois volitans) and the common lionfish (Pterois miles), have been established as invasive species off the East Coast of the United States and in the Caribbean.